2 * Routine for dissecting 802.3 (as opposed to D/I/X Ethernet) packets.
6 * Ethereal - Network traffic analyzer
7 * By Gerald Combs <gerald@ethereal.com>
8 * Copyright 1998 Gerald Combs
10 * This program is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public License
12 * as published by the Free Software Foundation; either version 2
13 * of the License, or (at your option) any later version.
15 * This program is distributed in the hope that it will be useful,
16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 * GNU General Public License for more details.
20 * You should have received a copy of the GNU General Public License
21 * along with this program; if not, write to the Free Software
22 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
30 #include <epan/packet.h>
31 #include "packet-ieee8023.h"
32 #include "packet-eth.h"
33 #include "packet-frame.h"
35 static dissector_handle_t ipx_handle;
36 static dissector_handle_t llc_handle;
39 dissect_802_3(int length, gboolean is_802_2, tvbuff_t *tvb,
40 int offset_after_length, packet_info *pinfo, proto_tree *tree,
41 proto_tree *fh_tree, int length_id, int trailer_id,
44 tvbuff_t *volatile next_tvb;
45 tvbuff_t *volatile trailer_tvb;
46 const char *saved_proto;
49 proto_tree_add_uint(fh_tree, length_id, tvb, offset_after_length - 2, 2,
52 /* Give the next dissector only 'length' number of bytes */
54 next_tvb = tvb_new_subset(tvb, offset_after_length, length, length);
55 trailer_tvb = tvb_new_subset(tvb, offset_after_length + length, -1, -1);
57 CATCH2(BoundsError, ReportedBoundsError) {
60 the packet doesn't have "length" bytes worth of
61 captured data left in it - or it may not even have
62 "length" bytes worth of data in it, period -
63 so the "tvb_new_subset()" creating "next_tvb"
68 the packet has exactly "length" bytes worth of
69 captured data left in it, so the "tvb_new_subset()"
70 creating "trailer_tvb" threw an exception.
72 In either case, this means that all the data in the frame
73 is within the length value, so we give all the data to the
74 next protocol and have no trailer. */
75 next_tvb = tvb_new_subset(tvb, offset_after_length, -1, length);
80 /* Dissect the payload either as IPX or as an LLC frame.
81 Catch BoundsError and ReportedBoundsError, so that if the
82 reported length of "next_tvb" was reduced by some dissector
83 before an exception was thrown, we can still put in an item
85 saved_proto = pinfo->current_proto;
88 call_dissector(llc_handle, next_tvb, pinfo, tree);
90 call_dissector(ipx_handle, next_tvb, pinfo, tree);
93 /* Somebody threw BoundsError, which means that dissecting the payload
94 found that the packet was cut off by a snapshot length before the
95 end of the payload. The trailer comes after the payload, so *all*
96 of the trailer is cut off - don't bother adding the trailer, just
97 rethrow the exception so it gets reported. */
101 /* Well, somebody threw an exception other than BoundsError.
102 Show the exception, and then drive on to show the trailer,
103 restoring the protocol value that was in effect before we
104 called the subdissector. */
105 show_exception(next_tvb, pinfo, tree, EXCEPT_CODE);
106 pinfo->current_proto = saved_proto;
110 add_ethernet_trailer(fh_tree, trailer_id, tvb, trailer_tvb, fcs_len);
114 proto_reg_handoff_ieee802_3(void)
117 * Get handles for the IPX and LLC dissectors.
119 ipx_handle = find_dissector("ipx");
120 llc_handle = find_dissector("llc");